relax SVN archive

Modified the cone_edge() function to accept the residue name as an argument.

Modified the cone_pdb() function so that the cone edge and cap are now the same residue.

Removed some debugging code.

Wrote the stitch_cap_to_cone() to join the cap of a cone to the cone edge.

This is being called from the specific_fns.n_state_model.cone_pdb() function.

The max_angle arg is now being respected. The generate_vector_dist() is complete.

Docstring fix for the generate_vector_dist() function.

Bug fix in the generate_vector_dist() function.

The centre of the distribution is called 'centre' and not 'R', as it used to be for the diffusion
tensor.

The call to generate_vector_dist() from cone_pdb() now passes in the 'CON' residue name.

A number of fixes for the new generate_vector_dist() function.

Shifted the code for generating the diffusion tensor geometric object into generate_vector_dist().

The code has been abstracted so that it can also be used to generate cone caps, or any other PDB
objects which can be generated by rotating and warping a sphere.